Pivot for snap-acting switch



Nov. 4, 1969 A. L. EHRENFELS ETAL PIVOT FOR SNAP-ACTING SWITCH FiledAug. 18, 1967 FIG. 3

mnzxroxs, AlFRE'D 1.. E/IRENFELS PAUL c. AAHLS I A 1 raAwE vs UnitedStates Patent 3,476,898 PIVOT FOR SNAP-ACTING SWITCH Alfred L.Ehrenfels, Cheshire, and Paul C. Kahl, Westfield, Conu., assignors toMaxson Electronics Corp., New York, N.Y., a corporation of New YorkFiled Aug. 18, 1967, Ser. No. 661,622 Int. Cl. H01h 21/40 US. Cl. 200-673 Claims ABSTRACT OF THE DISCLOSURE This invention relates generally tosnap-acting switches and more particularly to novel support means forthe thin leaf spring utilized as the actuating member for the movablecontact in a subminiature switch.

The present invention is directed to improvements in the structure ofsnap-acting switches of miniature size. These switches use a leaf springactuator for moving a contact between fixed terminals. The movablecontact is controlled according to the overcenter or toggle principlethat is well known in the art.

An example of the type switch that would utilize the present inventionis described and shown in US. Patent No. 3,144,529, issued on Aug. 11,1964, to J. J. Zemke et al. The switch is comprised of a body portionhaving terminals comolded therewith. A button extends through the coverof the switch and is actuated by a pivotally mounted lever. Internallythe button engages a cantilevered snap-acting spring that is mounted ona pivot member secured to the body of the switch. As shown in thedrawing of the aforementioned patent, the pivot member is comprised oftwo longitudinally extending, substantially parallel legs that supportthe tension legs of the spring at the ends thereof and a transverselypositioned leg at the opposite end of the pivot that supports thecompression leg of the spring. It will be noted that the ends of theupstanding, parallel legs are spaced apart and, in combination with thetransverse leg, provide a triangular support for the snap-acting spring.

The present invention is particularly characterized by an improved pivotmember that supports the snap-acting spring. In contrast to thestructure shown in the patent mentioned above, the present inventionprovides two spacedly opposed legs that pivotally support thecompression and tension members of the spring in a colinear manner.Essentially, the pivot is a U-shaped member having oppositely facingnotches in the oppositely facing ends of the legs thereof.

An overtravel stop for the pushbutton is provided by the central portionof the pivot that connects the two legs. In the aforementioned patentthe comparably functioning overtravel stop was the parallel side wallsthat supported the tension member on the snap-acting spring. Acomparison of the structure of this invention and the issued patent willreveal that the present invention is far simpler to fabricate and inaddition provides colinear support for the tension and compressionmembers of the spring whereas in the prior art the support was at three,triangulated po-in'ts.

Accordingly, it is an object of this invention to pro- ICC vide animproved pivot member for a snap action switch.

Another object of this invention is to provide a substantially U-shapedpivot member that supports the snap acting spring in a colinear manner.

A further object of this invention is to provide a pivot member thatmore rigidly and accurately supports the snap-acting spring member.

These and other features, objects and advantages of the invention will,in part, be pointed out with particularity and will, in part, becomeobvious from the following more detailed description of the invention,taken in conjunction with the accompanying drawing, which forms anintegral part thereof.

In the various figures of the drawing like reference charactersdesignate like parts.

In the drawing:

FIG. 1 is a perspective view of a prior art pivot bracket;

FIG. 2 is a perspective view of the pivot bracket constructed inaccordance with the teachings of the present invention;

FIG. 3 is a side elevational view of the present invention partly brokenaway and partly in section, illustrating the pivot bracket together andthe switch with which it is used;

FIG. 4 is a plan view of the new pivot bracket;

FIG. 5 is a longitudinal sectional view of a pivot member alone andtaken along line 55 of FIG. 4;

FIG. 6 is an end elevational view of the pivot member comprising thepresent invention;

FIG. 7 is another end elevational view of the pivot bracket the viewbeing taken opposite to that shown in FIG. 6; and

FIG. 8 is a plan view of the snap acting leaf spring used with thisinvention.

Referring now to FIG. 1 of the drawing, the prior art pivot 10 asexemplified by US. Patent No. 3,144,529 is comprised of a base portion12 that is secured to one of the switch terminals by means of a mountinghole 14. The pivot is provided with elongated side walls 16 that arespaced from each other in a plane parallel to the longitudinal axis ofthe leaf spring. A third, transversely located leg 18 is provided at theend of the pivot opposite to mounting hole 14. As may be seen in theaforementioned US. patent, the leaf spring is provided with a threepoint mounting by means of notches in each of the legs 16 and anoppositely facing notch in leg 18. Support for the tensioning portionsof the snap acting spring is provided by means of the notches 16a inlegs 16 and the compression portion of the spring is mounted in thenotch 18a in leg 18.

The dissimilarity between the present invention and the prior art willbe most readily apparent by a comparison of FIG. 1 and FIG. 2. Thepresent invention generally designated as reference character 20 in FIG.2 is comprised of a base portion 22 that extends in a planesubstantially parallel to the plane of the snap-acting switch. The baseis provided with an aperture 24 whereby it is secured to one of theterminals of the switch. Where appropriate, other means such as weldingmay be used to secure the pivot member to the terminal. A circularrecess 26 formed in the base portion during fabrication is used as anovertravel stop for the pushbutton. Legs 28 and 30 extend upwardly fromopposite ends of the base member. Leg 28 is provided with an inwardlyoffset portion 32 and transverse notches 34 and 36 are formedrespectively in leg portions 30 and 32. In the embodiment illustratedthe pivot member is blanked and formed from a 0.016 thick sheet ofbrass.

FIG. 3 illustrates the relationship of the pivot 20 with respect to theremainder of the switch elements. Switch member 40 is comprised of aplastic body member 42 having terminals 44, 46 and 48 comoldedtherewith. Fixed contacts 50 and 52 are secured to terminals 46 and 48,respectively, in any suitable manner. It will be seen that contacts 50,52 are spaced from each other and that the movable contact 54 of springmember 56 is positioned therebetween.

As may be seen in FIG. 8, spring member 56 is substantially rectangularin area and is provided with an enlarged rectangular opening 58 fromwhich extends two transversely spaced, elongated slots 60. The tensionlegs 62a and 62!) are defined by opening 58, there being a reativelynarrow transverse web 64 joining one end of the tension legs. A muchwider transverse web 66 joins the other end of the tension legs and alsoprovides a support member for contact 54. The compression member 68 isintegral with web 66 and extends parallel to the tension legs betweenslots 60 in a direction towards narrow web 64.

In the embodiment illustrated, transverse edge 64a of web 64 is disposedin transverse notch 34 of pivot leg 32. In a like manner, the freetransverse edge 68a of compression member 68 is positioned in notch 36of pivot leg 30.

Referring once again to FIG. 3, it will be seen that the pivot member,the spring and the contacts are completely enclosed by a cover member 70that is secured to the switch body 42. A button 72 extends through anopening in the top surface of the cover. The internal end of the button,which has been lengthened to cooperate with depression 26, bears againstthe two tension legs of the leaf spring in the area intermediate the twonotched support legs 30 and 32 of the pivot member.

Any suitable actuating means, such as a pivoted or resilient lever, aroller or the like may be used to depress the contact button by applyinga force in the direction of arrow a as shown in FIG. 3. The selection ofthe actuating means is made in accordance with the ultimate applicationof the switch.

In the prior art device the laterally extending tabs at the bottom,internal end of the contact button were arranged to coact with the topedges 16b of legs 16 in order to provide an overtravel stop. In thepresent invention upstanding side legs have been eliminated. However, inorder to provide an overtravel stop, depression 26 is provided in basemember 22. During stamping and forming of the pivot 20, means areincluded in the machine tool for making impression 26.

It will be appreciated from the drawing and the foregoing descriptionthat a more easily fabricated pivot member is provided for a snap actingswitch. Instead of the three point support found in the prior artstructure, the snap-acting spring of this invention is mounted ontransverse pivot points at the two ends of the pivot bracket. The springis still freely pivotable and yet is accurately located by means of thetwo elongated pivot means.

While the leaf spring is not a part per se of this invention, it isessential that the pivot member be accurately fabricated in orderto'permit the spring to function with its usual and well knowncharacteristics.

There has been disclosed heretofore the best embodiment of the inventionpresently contemplated. It is to be understood, however, that variouschanges and modifications may be made bythose skilled in the art withoutdeparting from the spirit of the invention.

What is claimed is:

1. A switch comprising a housing, a snap-acting spring havbing acontact, said spring being provided with an opening therethrough, a pairof spaced fixed contacts, a U-shaped bracket support means for saidspring, the spaced legs of said bracket constituting a first memberhaving a first notch in the outer surface thereof supporting the tensioncomponent of said spring in said first notch and a secondmember having asecond notch in the outer surface thereof .supporting the compressioncomponent of said spring in said second notch, the bight portion of saidU-shaped bracket support means interconnecting said first .and secondmembers and being provided with a stop means, and actuating meansprojecting through said housing and the opening in said spring whileengaging a portion of the latter and extending below the plane of saidspring a distance to ensure abutment of said stop means thereby limitingthe travel of said actuating means in one direction when said contactengages a selected fixed contact.

2. A switch as claimed in claim 1 wherein said spring has asubstantially rectangular opening therein, said compression component ofsaid spring being a struck-out element projecting into said opening, andthe tension component of said spring being the transverse web of saidspring at the opposite side of said opening from said struck-outelement.

3. A switch as claimed in claim 1 wherein said stop means is a recess insaid bight portion and is integral with the latter.

References Cited UNITED STATES PATENTS 2,594,216 4/1952 Roeser.2,659,238 11/1953 Martin. 2,743,331 4/1956 Lauder et al. 2,985,7385/1961 Baak.

FOREIGN PATENTS 1,185,042 2/1959 France.

ROBERT S. MACON, Primary Examiner D. SMITH, JR., Assistant Examiner

